The present invention generally relates to coatings for turbine engine components, particularly, wear coatings for turbine engine components.
Wear coatings have found various applications in turbine engines. For example, abrasive, wear-resistant coatings are deposited on the outer tips of turbine blades. Such coatings are generally employed to decrease the rate of wear of the blade due to contact of the blade with its surrounding shroud. Other wear coatings are placed on leading edges of turbine blades to decrease wear (by erosion) due to contact with environmental particulates (e.g., dirt, sand) that enter the turbine engine during operation.
Still another type of wear coating is placed on parts of the turbine engine that are susceptible to wear due to part-to-part contact during operation. For example, in the high pressure turbine (HPT) and low pressure turbine (LPT) sections of an engine, wear coatings are placed on nozzle wear pads that rub against an adjacent structure, such as a shroud hanger or a pressure balance seal.
In the latter form of wear coating, to address part-to-part contact and wear, the coating is generally applied by a thermal spray process, such as plasma spraying. Several disadvantages exist with thermal spray processing. For example, the part to be treated must be masked in order to prevent application of the wear coating on portions of the component that are not subject to part-to-part wear. In addition, some regions of a part are difficult to access with thermal spray equipment. Also, the coating application requires time consuming processing.
Accordingly, a need exists in the art for improved techniques for depositing wear coatings. In addition, a need exists in the art for wear coatings that are resistant to spallation and which have requisite wear resistance.
According to an embodiment of the present invention, a turbine engine component includes a substrate, and a wear coating on the substrate, the wear coating including wear-resistant particles in a matrix phase, the wear-resistant particles being formed of a chrome carbide or a cobalt alloy.
Embodiments of the present invention also include methods for coating a substrate, such as a turbine engine component. In one method a preform is attached to the substrate, the preform containing braze alloy and wear-resistant particles. The preform is then heated and fused to the substrate to form the wear-resistant coating.